19.3.3.5 Defining an NDB Cluster Management Server

The [ndb_mgmd] section is used to configure
the behavior of the management server. If multiple management
servers are employed, you can specify parameters common to all
of them in an [ndb_mgmd default] section.
[mgm] and [mgm default]
are older aliases for these, supported for backward
compatibility.

All parameters in the following list are optional and assume
their default values if omitted.

Note

If neither the ExecuteOnComputer nor the
HostName parameter is present, the default
value localhost will be assumed for both.

Each node in the cluster has a unique identity. For a
management node, this is represented by an integer value in
the range 1 to 255, inclusive. This ID is used by all
internal cluster messages for addressing the node, and so
must be unique for each NDB Cluster node, regardless of the
type of node.

Note

Data node IDs must be less than 49. If you plan to deploy
a large number of data nodes, it is a good idea to limit
the node IDs for management nodes (and API nodes) to
values greater than 48.

The use of the Id parameter for
identifying management nodes is deprecated in favor of
NodeId. Although
Id continues to be supported for backward
compatibility, it now generates a warning and is subject to
removal in a future version of NDB Cluster .

Each node in the cluster has a unique identity. For a
management node, this is represented by an integer value in
the range 1 to 255 inclusive. This ID is used by all
internal cluster messages for addressing the node, and so
must be unique for each NDB Cluster node, regardless of the
type of node.

Note

Data node IDs must be less than 49. If you plan to deploy
a large number of data nodes, it is a good idea to limit
the node IDs for management nodes (and API nodes) to
values greater than 48.

NodeId is the preferred parameter name to
use when identifying management nodes. Although the older
Id continues to be
supported for backward compatibility, it is now deprecated
and generates a warning when used; it is also subject to
removal in a future NDB Cluster release.

Specifying this parameter defines the hostname of the
computer on which the management node is to reside. To
specify a hostname other than localhost,
either this parameter or
ExecuteOnComputer is required.

Not every facility is necessarily supported by every
operating system.

SYSLOG:facility=syslog

FILE pipes the cluster log output to
a regular file on the same machine. The following values
can be specified:

filename: The name of the log
file.

The default log file name used in such cases is
ndb_nodeid_cluster.log.

maxsize: The maximum size (in
bytes) to which the file can grow before logging
rolls over to a new file. When this occurs, the old
log file is renamed by appending
.N to the file name,
where N is the next
number not yet used with this name.

maxfiles: The maximum number of
log files.

FILE:filename=cluster.log,maxsize=1000000,maxfiles=6

The default value for the FILE
parameter is
FILE:filename=ndb_node_id_cluster.log,maxsize=1000000,maxfiles=6,
where node_id is the ID of
the node.

It is possible to specify multiple log destinations
separated by semicolons as shown here:

This parameter is used to define which nodes can act as
arbitrators. Only management nodes and SQL nodes can be
arbitrators. ArbitrationRank can take one
of the following values:

0: The node will never be used as an
arbitrator.

1: The node has high priority; that
is, it will be preferred as an arbitrator over
low-priority nodes.

2: Indicates a low-priority node
which be used as an arbitrator only if a node with a
higher priority is not available for that purpose.

Normally, the management server should be configured as an
arbitrator by setting its ArbitrationRank
to 1 (the default for management nodes) and those for all
SQL nodes to 0 (the default for SQL nodes).

You can disable arbitration completely either by setting
ArbitrationRank to 0 on all management
and SQL nodes, or by setting the
Arbitration
parameter in the [ndbd default] section
of the config.ini global configuration
file. Setting
Arbitration causes
any settings for ArbitrationRank to be
disregarded.

An integer value which causes the management server's
responses to arbitration requests to be delayed by that
number of milliseconds. By default, this value is 0; it is
normally not necessary to change it.

This specifies the directory where output files from the
management server will be placed. These files include
cluster log files, process output files, and the daemon's
process ID (PID) file. (For log files, this location can be
overridden by setting the FILE parameter
for LogDestination
as discussed previously in this section.)

The default value for this parameter is the directory in
which ndb_mgmd is located.

Specify the interval between heartbeat messages used to
determine whether another management node is on contact with
this one. The management node waits after 3 of these
intervals to declare the connection dead; thus, the default
setting of 1500 milliseconds causes the management node to
wait for approximately 1600 ms before timing out.

Note

After making changes in a management node's
configuration, it is necessary to perform a rolling restart of
the cluster for the new configuration to take effect.